As materials having bioactive functions, there have been proposed a variety of materials. For example, there are given polyphenols as those having bioactive functions, such as an antioxidative effect, an antihypertensive effect, and a hepatic function-improving effect. A chlorogenic acid, which is one of the polyphenols, has been reported to have a high antihypertensive effect, and is expected to find applications in supplements and food and drink.
As a material containing a large amount of the chlorogenic acid, there are given coffee beans. A chlorogenic acid-containing composition obtained by extraction from the coffee beans has been conventionally investigated with regard to, for example, an increase in recovery rate of the chlorogenic acid, a reduction in impurities, such as caffeine, an improvement in taste and flavor, and an improvement in color. For example, as a method of producing a purified chlorogenic acid that is so stable as not to form precipitates immediately after production, and that does not form secondary precipitates even when an extract is subjected to heat sterilization, and further to long-term storage, there has been proposed a method involving concentrating a coffee extract to a refractive sugar content (20° C.) of Bx8° or more as solids concentration, and then bringing the concentrated extract into contact with acid clay and/or activated clay. It has been reported that the resulting purified chlorogenic acid has reductions in caffeine and solids through treatment, but does not change in composition of organic acids, such as malic acid and acetic acid, and has a refreshing taste and flavor without coarseness (Patent Document 1).
(Patent Document 1) JP-A-2008-266144